scholarly journals The Development of Log Aesthetic Patch and Its Projection onto the Plane

Mathematics ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 160
Author(s):  
Yee Meng Teh ◽  
R. U. Gobithaasan ◽  
Kenjiro T. Miura ◽  
Diya’ J. Albayari ◽  
Wen Eng Ong
Keyword(s):  
Outer Part ◽  
Geodesic Curvature ◽  
Surface Patch ◽  
Hyperbolic Paraboloid ◽  
Shipbuilding Industry ◽  
First Derivative ◽  
Cold Bending ◽  
Lines Of Curvature ◽  
New Type ◽  
Boundary Curves

In this work, we introduce a new type of surface called the Log Aesthetic Patch (LAP). This surface is an extension of the Coons surface patch, in which the four boundary curves are either planar or spatial Log Aesthetic Curves (LACs). To identify its versatility, we approximated the hyperbolic paraboloid to LAP using the information of lines of curvature (LoC). The outer part of the LoCs, which play a role as the boundary of the hyperbolic paraboloid, is replaced with LACs before constructing the LAP. Since LoCs are essential in shipbuilding for hot and cold bending processes, we investigated the LAP in terms of the LoC’s curvature, derivative of curvature, torsion, and Logarithmic Curvature Graph (LCG). The numerical results indicate that the LoCs for both surfaces possess monotonic curvatures. An advantage of LAP approximation over its original hyperbolic paraboloid is that the LoCs of LAP can be approximated to LACs, and hence the first derivative of curvatures for LoCs are monotonic, whereas they are non-monotonic for the hyperbolic paraboloid. This confirms that the LAP produced is indeed of high quality. Lastly, we project the LAP onto a plane using geodesic curvature to create strips that can be pasted together, mimicking hot and cold bending processes in the shipbuilding industry.

A study on timelike circular surfaces in Minkowski 3-space

2020 ◽  
Vol 17 (06) ◽  
pp. 2050074
Author(s):  
Rashad A. Abdel-Baky ◽  
Nadia Alluhaibi ◽  
Akram Ali ◽  
Fatemah Mofarreh
Keyword(s):  
Geodesic Curvature ◽  
Parameter Family ◽  
Lines Of Curvature ◽  
Constant Radius ◽  
Spherical Indicatrix ◽  
New Type ◽  
Circular Surface ◽  
Fixed Radius

This paper studies a smooth one-parameter family of standard Lorentzian circles with fixed radius. Such a surface is called a timelike circular surface with constant radius. We call each circle a generating circle. A new type of timelike circular surfaces was identified and coined as the timelike tangent circular surface. The new timelike tangent circular surface has the property of all generating circles being lines of curvature and its Gaussian and mean curvatures being independent of the geodesic curvature of the spherical indicatrix.

scholarly journals Curvature effects on phase transitions in chiral magnets

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Kostiantyn Yershov ◽  
Volodymyr Kravchuk ◽  
Denis Sheka ◽  
Ulrich Roessler
Keyword(s):  
Domain Wall ◽  
Exchange Interactions ◽  
Critical Value ◽  
Wall Structure ◽  
Cylinder Axis ◽  
Exact Analytical Solutions ◽  
Curvature Effects ◽  
New Type ◽  
Boundary Curves ◽  
Moriya Interaction

Periodical equilibrium states of magnetization exist in chiral ferromagnetic films, if the constant of antisymmetric exchange (Dzyaloshinskii–Moriya interaction) exceeds some critical value. Here, we demonstrate that this critical value can be significantly modified in curved film. The competition between symmetric and antisymmetric exchange interactions in a curved film can lead to a new type of domain wall which is inclined with respect to the cylinder axis. The wall structure is intermediate between Bloch and Néel ones. The exact analytical solutions for phase boundary curves and the new domain wall are obtained.

Research on the Tribological Properties of SF Polymer Water-Lubricated Bearings

2010 ◽  
Vol 150-151 ◽  
pp. 102-107 ◽  
Author(s):  
Zhu Xin Wu ◽  
Lin Liu Zheng ◽  
Fa Xiao Fan
Keyword(s):  
Friction Coefficient ◽  
Tribological Properties ◽  
Load Capacity ◽  
Low Friction ◽  
Swelling Properties ◽  
Shipbuilding Industry ◽  
Simulation Testing ◽  
New Type ◽  
Water Swelling ◽  
High Load Capacity

In the paper, the SF polymer water lubricated bearings is taken as the research objects. Both material testing and bearing simulation testing are carried out to research the tribological properties of bearings including water swelling properties, friction coefficient, and wear-resistant properties mainly. The results show that the SF material, which is a new type of material used in water lubricated tail bearing, has the characteristics of low friction coefficient, high load capacity, good wear-resistance, excellent self-lubricating properties, and low water swelling, which has a broad application in the shipbuilding industry.

Research on Deformation Monitoring of Large Span Hyperbolic-Paraboloid Composite Torsional Shell

2010 ◽  
Vol 163-167 ◽  
pp. 2819-2823
Author(s):  
Hui Deng ◽  
Guang Jian Xiao ◽  
Yu Cao
Keyword(s):  
Deformation Monitoring ◽  
Type Structure ◽  
Hyperbolic Paraboloid ◽  
Construction Monitoring ◽  
Large Span ◽  
Long Span ◽  
Deformation Parameters ◽  
New Type ◽  
Measured Deformation ◽  
Construction Optimization

Long span hyperbolic-paraboloid composite torsional shell is a new type structure. In order to find out actual deformation of the roof during construction, monitoring is carried out based on deformation monitoring scheme that was put forward in this paper, and deformation parameters and characteristic of the roof are obtained. It is proved that the measured deformation values are basically consistent with the simulation calculations, and the results show that the scheme is correct and feasible, meanwhile, all of monitoring results are helpful for future analog calculation, design and construction optimization of similar project.

Distortion Control and Prevention by Fabrication Techniques in Cold Bent Steel Frame with Perforated Web

2021 ◽  
Vol 37 (01) ◽  
pp. 37-44
Author(s):  
Peiyong Li ◽  
Zheng Tang ◽  
Yuwen Huang ◽  
Yunpeng Wang ◽  
Chong Wang
Keyword(s):  
Offshore Structures ◽  
Efficient Production ◽  
Deformation Characteristics ◽  
Shipbuilding Industry ◽  
Cold Bending ◽  
Distortion Control ◽  
Bending Process ◽  
Fabrication Procedure ◽  
Control And Prevention ◽  
The Web

Cutouts are widely used in ships and offshore structures. Cutouts of big size are used mainly for inspection, passing pipes, and weight reduction. Some cutouts of small size may be used for various purposes, such as water hole in the web of stiffeners. The stiffeners with perforated web are the most commonly adopted structure members in the shipbuilding industry, and they are mainly fabricated by cutting and bending the frame to meet the requirements of desired design configuration. In ship production, the manufacture of the curved stiffener with holes is desirable to perforate first and then to bend the frame. This fabrication procedure is adopted for efficient production because of the layout of the production line. However, structural distortion and damage may occur during cold bending of the frames with perforated web, such as necking, wrinkling, and even crack initiation. This problem should be solved in ship production. In this study, cold bending experiments and finite element simulations were performed to analyze the deformation characteristics of curved frames with cutouts. A fabrication method is proposed to control the deformation in the cutouts during the bending process. In this method, the block cut out during the first step is filled in the hole and afterward the frame is bent. The results show that this method can control well the deformation localized around the hole during the bending process. It offers an important guidance for cold bending steel frames in ship production.

A CHARACTERIZATION OF THE CATENOID AND HELICOID

2013 ◽  
Vol 24 (06) ◽  
pp. 1350045 ◽  
Author(s):  
CARLOS M. C. RIVEROS ◽  
ARMANDO M. V. CORRO
Keyword(s):  
Minimal Surface ◽  
Minimal Surfaces ◽  
Geodesic Curvature ◽  
Lines Of Curvature ◽  
Asymptotic Lines

In this paper we show that a connected non-planar minimal surface whose asymptotic lines have the same geodesic curvature up to sign is a catenoid. As an application of this result we show that a connected non-planar minimal surface whose lines of curvature have the same geodesic curvature up to sign is a helicoid. Moreover, we show that the coordinates curves of the associate minimal surfaces to catenoid have the same geodesic curvature up to sign.

CONSTRUCTING CONSTRAINED DELAUNAY TETRAHEDRALIZATIONS OF VOLUMES BOUNDED BY PIECEWISE SMOOTH SURFACES

2011 ◽  
Vol 21 (05) ◽  
pp. 571-594 ◽  
Author(s):  
SERGE GOSSELIN ◽  
CARL OLLIVIER-GOOCH
Keyword(s):  
Poor Quality ◽  
Sampling Procedure ◽  
Piecewise Smooth ◽  
Surface Patch ◽  
Smooth Surfaces ◽  
Delaunay Refinement ◽  
Protection Scheme ◽  
Delaunay Tetrahedralization ◽  
Boundary Curves ◽  
Refinement Algorithm

This article presents an algorithm to construct constrained Delaunay tetrahedralizations of geometric domains bounded by piecewise smooth surfaces. Meshes are built from the bottom-up by first discretizing the boundary curves and then by sampling the smooth surfaces. The sampling procedure refines the Delaunay triangulation restricted to these surfaces, targeting topological violations and poor quality triangles. Unlike previously published algorithms adopting a similar approach, we propose to sample each smooth surface patch independently. This obviates the need for a boundary protection scheme around small dihedral angles in the input and can also lead to coarser constraining triangulations. Starting from a Delaunay tetrahedralization of the point samples, a combination of mesh reconfigurations and vertex insertions is then used to obtain a tetrahedralization constrained to the boundary surfaces. The algorithm is designed to produce tetrahedralizations that can be used in conjunction with a Delaunay refinement algorithm implemented on a Bowyer-Watson framework.

The Microstructure of Shock-Synthesized Diamond

1967 ◽  
Vol 25 ◽  
pp. 324-325
Author(s):  
Lucien F. Trueb
Keyword(s):  
Single Crystals ◽  
Preferred Orientation ◽  
High Magnification ◽  
Texture Pattern ◽  
Shock Process ◽  
New Type ◽  
Diffraction Diagram

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.

New type electron gun with electrostatic and electromagnetic lenses

1978 ◽  
Vol 36 (1) ◽  
pp. 62-63
Author(s):  
T. Ichinokawa ◽  
H. Maeda
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Optimum Condition ◽  
Bias Voltage ◽  
Electron Gun ◽  
Charge Effect ◽  
Micro Fabrication ◽  
Maximum Brightness ◽  
New Type ◽  
The Ideal

I. IntroductionThermionic electron gun with the Wehnelt grid is popularly used in the electron microscopy and electron beam micro-fabrication. It is well known that this gun could get the ideal brightness caluculated from the Lengumier and Richardson equations under the optimum condition. However, the design and ajustment to the optimum condition is not so easy. The gun has following properties with respect to the Wehnelt bias; (1) The maximum brightness is got only in the optimum bias. (2) In the larger bias than the optimum, the brightness decreases with increasing the bias voltage on account of the space charge effect. (3) In the smaller bias than the optimum, the brightness decreases with bias voltage on account of spreading of the cross over spot due to the aberrations of the electrostatic immersion lens.In the present experiment, a new type electron gun with the electrostatic and electromagnetic lens is designed, and its properties are examined experimentally.

A new type of defect structure in 124-superconducting oxide revealed by HREM

1991 ◽  
Vol 49 ◽  
pp. 1092-1093
Author(s):  
R. Sharma ◽  
B.L. Ramakrishna ◽  
N.N. Thadhani ◽  
D. Hianes ◽  
Z. Iqbal
Keyword(s):  
Shock Wave ◽  
Defect Structure ◽  
Neutron Radiation ◽  
Weak Links ◽  
Defect Structures ◽  
New Materials ◽  
New Type ◽  
Current Densities ◽  
Processing Techniques ◽  
Microstructural Studies

After materials with superconducting temperatures higher than liquid nitrogen have been prepared, more emphasis has been on increasing the current densities (Jc) of high Tc superconductors than finding new materials with higher transition temperatures. Different processing techniques i.e thin films, shock wave processing, neutron radiation etc. have been applied in order to increase Jc. Microstructural studies of compounds thus prepared have shown either a decrease in gram boundaries that act as weak-links or increase in defect structure that act as flux-pinning centers. We have studied shock wave synthesized Tl-Ba-Cu-O and shock wave processed Y-123 superconductors with somewhat different properties compared to those prepared by solid-state reaction. Here we report the defect structures observed in the shock-processed Y-124 superconductors.

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